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                [Usaco2007 Mar]Balanced Lineup                </h1>
                <p>时间限制：5s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：64MB</p>			</div>
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                                <h3>题目描述</h3><p><p>Farmer John 决定给他的奶牛们照一张合影，他让 N (1 &le; N &le; 50,000) 头奶牛站成一条直线，每头牛都有它的坐标(范围: 0..1,000,000,000)和种族(0或1)。 一直以来 Farmer John 总是喜欢做一些非凡的事，当然这次照相也不例外。他只给一部分牛照相，并且这一组牛的阵容必须是&ldquo;平衡的&rdquo;。平衡的阵容，指的是在一组牛中，种族0和种族1的牛的数量相等。 请算出最广阔的区间，使这个区间内的牛阵容平衡。区间的大小为区间内最右边的牛的坐标减去最做边的牛的坐标。 输入中，每个种族至少有一头牛，没有两头牛的坐标相同。</p></p><hr/><h3>输入格式</h3><p><p>行 1: 一个整数: N 行 2..N + 1: 每行两个整数，为种族 ID 和 x 坐标。</p></p><hr/><h3>输出格式</h3><p><p>行 1: 一个整数，阵容平衡的最大的区间的大小。</p></p><hr/><h3>样例输入</h3><pre>7
0 11
1 10
1 25
1 12
1 4
0 13
1 22
</pre><hr/><h3>样例输出</h3><pre>11
输入说明 

有7头牛，像这样在数轴上。 


            1                 1  0  1  0                          1        1
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
输出说明 

牛 #1 (at 11), #4 (at 12), #6 (at 13), #7 (at 22) 组成一个平衡的最大的区间，大小为 22-11=11 个单位长度。 

                                 <--------     平衡的     -------->
            1                 1  0  1  0                          1        1
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>Silver</p>
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